The present invention relates to an apparatus for irradiating a substrate, the apparatus comprising a receptacle for the substrate to be irradiated, the substrate having a circular irradiation surface, and an optical emitter having at least one emitter tube. The emitter tube comprises an illumination length having a middle section and two end sections and is arranged in an illumination plane that extends parallel to the irradiation surface, wherein the length of the middle section accounts for at least 50% of the illumination length. The receptacle and the optical emitter can be moved with respect to each other.
The present invention further relates to a use of the apparatus according to the invention for irradiating a substrate.
Such devices are used, for example, for drying of paints and lacquers, for curing coatings, for heating food products or for the processing of semiconductor wafers.
Known apparatuses for irradiating a substrate comprise a process chamber for accommodation of a substrate to be irradiated and at least one optical emitter, which is often designed in the form of an infrared emitter. Usually, a uniform irradiation of the substrate surface and a homogeneous temperature distribution inside the substrate are important for the process result.
An irradiation apparatus of the aforementioned type is known from German published patent application DE 100 51 125 A1, which discloses a rapid heating system for semiconductor wafers. The rapid heating system has a rotatably mounted holder for a substrate having a circular irradiation surface and multiple infrared emitters having a linear, cylindrical-elongated emitter tube made of quartz glass and a filament made of tungsten, whose ends are provided with electrical connection elements for the supply of electrical power via power supply wires. To ensure homogeneous irradiation of the substrate on all sides, the infrared emitters are arranged in two irradiation planes, namely above and below the irradiation surface. The infrared emitters in the irradiation planes are mounted next to each other in parallel and, taken together, form a two-dimensional emitter.
Due to the two-dimensional array of infrared emitters, a plurality of infrared emitters are provided in the irradiation apparatus with respect to the surface to be irradiated. The irradiation apparatus also has very high radiated power per unit area. To achieve a homogeneous distribution of the heating power, the heating power of the infrared emitters must therefore be coordinated. This applies especially to the edges of the irradiation surface. An irradiation apparatus having a two-dimensional array of infrared emitters therefore necessitates a complex control technology.
Moreover, a two-dimensional array of infrared emitters of this type having a linear, elongated emitter tube is disadvantageous from the point of view of design. This is particularly the case when the space available for positioning the infrared emitters is limited, confined or difficult to access.